PROJECT SUMMARY/ABSTRACT Reading is one of the most important skills learned in early childhood. Unfortunately, bilingual learners in the US often fail to meet national standards in reading achievement (Hemphill, 2011). This proposal seeks to understand how bilingualism affects child literacy to advance science and inform individualized approaches to reading instruction and precision treatment of dyslexia for the growing numbers of young US bilinguals. The study's primary objective is to explain the effects of bilingualism on children's neural architecture for learning to read. This proposal advances current literacy perspectives (Lexical Quality Model; Perfetti & Hart, 2002) suggesting that learning to read requires the interaction between the neurocognitive systems linking children's representations of word sounds, meanings and orthographic forms so children can form sound-to- print and meaning-to-print associations. However, different languages put more emphasis on different associations. Learning to read in Spanish prompts children to form stronger sound-to-print associations, while Chinese literacy prompts children to form stronger meaning-to-print associations. We draw upon this cross- linguistic evidence to examine bilingualism through the guiding hypothesis that bilinguals' developing neurocognitive systems are affected by their proficiency with characteristics of the languages being acquired. To test this hypothesis, we will use behavioral and functional Near Infrared Spectroscopy (fNIRS) neuroimaging measures in each of the children's languages, testing Chinese-English bilinguals, Spanish- English bilinguals and English monolinguals ages 6?9 (N=300). We will also test a subset of these children longitudinally (N=150). All children will be attending English-only schools. The bilingual children will vary in heritage literacy instruction received at home or through partnering afterschool programs. Aim 1 is to determine how bilingualism impacts children's neural architecture for learning to read. Aim 2 is to map the neurocognitive trajectory for learning to read for the bilingual child. This theory-guided approach will provide a solid empirical basis to (1) uncover neurocognitive processes that support emergent English literacy in bilingual contexts; (2) inform theories of learning to read by providing principled evidence on bilingual acquisition of typologically-contrasting languages; (3) specify individual differences in the development of phonological and semantic literacy pathways critical to reading success. Such understanding will allow us to draw inferences about cross-linguistic learning experiences and sources of variation in bilinguals' strengths and weaknesses in learning to read in English. Taken together, the comprehensive behavioral and neuroimaging evidence on emergent dual-language and reading competence will provide rich information to inform theory, educational practices, and clinical approaches for a growing number of young bilingual and minority language learners.